Rx400h Not Up To Specs

[SW03ES]

It appears that most RX400h owners posting information are reporting better highway MPG than city. Example, 28 hwy, 24 average.

Many owners are seemingly struggling to find the "proper" way to drive the RX400h in order to get better fuel economy....

Puzzling, VERY!

The Prius DEFINITELY has better city fuel economy than highway.

I have NEVER heard anyone say that special driving techniques are needed for the Prius.

Yet both the Prius and the RX400h use the very same Toyota hybrid design concept.

What went wrong?

←

LMAO, go to www.priuschat.com or www.priusonline.com they have HUGE discussions about the "proper" way to drive the car and it makes the difference between the 55MPG numbers they get and the 47mpg numbers I get. If you've never heard anyone suggest special driving techniques to maximize mileage on the Prius you must have never read a thread on any Prius online chat group or forum. "head in the sand" kinda thing.

Also many members who get routinely better highway mileage than city, including us.

The issue is with Toyota's style Hybrid the mileage is not consistent across drivers or locations nor is it reliable from one day to the next. Not a problem with the RX400h, its just a fact of life with their system. Honda's system doesn't have this problem as the ICE never shuts off and the electric motor and engine always work in harmony. The result is not as impressive EPA MPG figures but MPG figures that are much more reliable and consistent.

[the-headless_horseman]

Actually the throttle plate is "airtight". Most modern day cars have a variable idle air bypass path around the throttle plate that can be restricted by the ECU to attain the correct idle RPM under differing idle loads, A/C, power stearing, etc.

←

I think we need to clarify something here....

Highway mileage is just that...cruising at say 55-75 mph...

City mileage can be interpreted a few ways...if you drive in a major surburban/city area and are in stop and go traffic all the time, your electric motors are all you need...you'll get over 30 mpg...this is because you are not often times going over 20 mph...

However, if you live in the suburbs and have to start and stop on 35/45/50 mph roads, then you are going to get about 23-25 mpg...reason is because the electric motor is not enough to give you power up to the speed you need...then, top it off with frequent stops at lights and having to start up again...this will adversely affect your mileage...

So, if we can set that straight, we can see why the highway mileage is better unless we are talking about bumper to bumper traffic for long periods of time...'normal' suburb driving is not that efficient...unless you drive late at night and don't hit all the lights...can coast a lot!

Headless

[Lexusfreak]

I have had my RX for over a week now...driven it about 350 miles.   I have found that if you drive the car no more than 65 mph on the highway (and with cruise) or on flat ground with no need to accelerate, you can get good mileage...otherwise, the car, so far, is a bust.

The reason I say this?

I have not seen any numbers above 24 mpg on my car.  No matter how gingerly or hard I drive it, I can't get the mpg up...whether I accelerate like a grandma or hit the gas 'briskly', the car's gas motor seems to suck down gas...and it seems to run virtually all the time.

Lexus stated 31/27...that's fine and dandy...but under what conditions?  I don't think drivers should have to change their driving style to get this mileage...as is the case with ANY car, if you drive it a little harder, you lose some efficiency...what's apparent with a hybrid is if you accelerate a little too much, you get lousy mileage...period!

I don't know how Lexus got away with advertising good mileage with this vehicle.  I'm seeing better performance at a tremendously greater price, and with very little efficiency gain.

If I were to receive the 31/27 with 'normal' driving conditions, I'd be very happy.  Problem is that I'm driving around at about 22-23 mpg easing the car around as carefully as I can so as to not 'over-engage' the gas motor.

I feel very misled and as of this point in time, very, very unhappy with this vehicle.  I appreciate the navi system, bluetooth, and other toys, but they pale in comparison to the importance I stressed on the improved mileage for the vehicle.

I gloated to everyone that I was getting a luxury hybrid SUV that would be getting me near 30mpg...now I'm embarassed to tell anyone I even bought the car...there is nothing special about the hybrid system other than a lot of technology...

A breakin period is, of course, in order...however, the likelihood of going from 23 mpg to near 30 is probably very slim...I guess to get there I'll always have to be driving down hill....this is pathetic.

I think Lexus has done itself a HUGE dis-service with this vehicle.  I can't imagine most people will be happy with its lower than advertised mpg...all for thousands more.  As of this date, this car is a bust...too much money for too little of what Lexus said it would do.

Once J.D. Power gets a hold of people like me, I don't see Lexus sitting number one much longer!

I am so very disappointed...I guess I should have waited a few years to see how the hybrids would turn out...had I known they'd be so disappointing, I would have put my $50,000+ somewhere else...should've waited for next MDX generation with cylinder cut-off...likely to get true 28 mpg like the Honda Odyssey...and it'll be about $10,000 less, with more room....

Lexus should be ashamed of this vehicle!

Headless

←

From your initial post, I don't think you have given enough time & miles for the vehicle to be properly 'broken in'. :whistles:

How many miles are currently on the RX?

[SW03ES]

LF- He doesn't want to be happy with it.

[lexusjohn]

LF- He doesn't want to be happy with it.

←

Yep would have to agree.

UK owner of the NEW GS300SE, waiting for the GS450h :whistles:

[CKK]

The other thing that an earlier post mentioned was how this car appears to have a cruise-control that does far better than the car allows the driver to do with respect to mixing ICE and electric.

←

Yes, I agree completely. The cars seems to use the engine more smoothly under cruise.

I believe it has other programming to improve efficiency as well. I carefully observed what I think is an interesting algorithm at work. With the cruise on, the car holds speed pretty accurately, but when you crest a hill and the engine turns off to coast, the cruise allows the speed to coast down 5mph before restarting the engine and accelerating back to the set speed. Furthermore, while it is coasting down, it runs the electric motor only (warp stealth) to try to maintain speed as long as possible before restarting the engine. To observe this, set the cruise high, 75 or so, and set the speedometer display to the energy use graphicto see speed and energy together at a glance. The system is smart. I had assumed that I could do better than any cruise system by anticipating hills and blending the speed, but this is not just a dumb setpoint only cruise control.

I have taken to driving with cruise as much as possible, using the stalk to accelerate and coast within reason in light traffic.

I really think this car should have a sport button that give you the engine always available for quick acceleration, and an economy button with much less aggressive software. One of the major benefits of all these computers is that it should be able to be two different cars at whim of the driver.

←

I tried using the cruise control over the last two days (I've never been a fan of CC) given these experiences and the difference in mpg is DRAMATIC. I drive 20 miles to work each way on the highway, and my average mpg has been about 35! It is clear that the algorithm for the CC is done to optimize battery usage. I am very impressed.

I also echo the concern of a previous poster that noticed that other drivers seem unaware of the RX400h's approach, particularly in parking lots as they back out. I have had two near-accidents as drivers glanced in the opposite direction, and because they did not hear me coming, just kept on backing up. Very disconcerting.

[Lexusfreak]

LF- He doesn't want to be happy with it.

←

After reading his posts over a second time I would have to agree with you sw! B)

[the-headless_horseman]

[

←

From your initial post, I don't think you have given enough time & miles for the vehicle to be properly 'broken in'. :whistles:

How many miles are currently on the RX?

←

I have over 1700 miles on it now...performing better than it was...the original 22.9 mpg is now almost 25 mpg...trying to coast a little more but using power when need it...highway about 27 mpg, depending on speed and road conditions...

Headless

[Lexusfreak]

I have over 1700 miles on it now...performing better than it was...the original 22.9 mpg is now almost 25 mpg...trying to coast a little more but using power when need it...highway about 27 mpg, depending on speed and road conditions...

Headless

←

More accurate fuel economy numbers will start showing up after your first oil change at 5,000+ miles at least. The engine is still getting 'broken in' dude (all brand new cars have higher fuel consumption because of this, hybrid or not) & for some reason I feel that you have set your expectations so high that you are your own worst enemy because of it. Be a bit more patient on this & relax!........and start to enjoy your new ride more, she is a beautiful piece of machinery.

[dreamchaserflorida]

I have over 1700 miles on it now...performing better than it was...the original 22.9 mpg is now almost 25 mpg...trying to coast a little more but using power when need it...highway about 27 mpg, depending on speed and road conditions...

Headless

←

More accurate fuel economy numbers will start showing up after your first oil change at 5,000+ miles at least. The engine is still getting 'broken in' dude (all brand new cars have higher fuel consumption because of this, hybrid or not) & for some reason I feel that you have set your expectations so high that you are your own worst enemy because of it. Be a bit more patient on this & relax!........and start to enjoy your new ride more, she is a beautiful piece of machinery.

←

Patience is virtue.

My daughter has 1,200 miles now on her RX 400h... including about a 250 miles highway trip. She reports approx 26 mpg without special approaches in driving.

I still only have 200 miles on mine in the two weeks I have had the car so the 23 mpg I have had is a moot report.

If I had wanted better fuel consumption as offered by a cheaper, smaller, less powerful hybrid, then I would drive a Prius... if I wanted a luxury class SUV hybrid like the RX 400h, I would get that and forfeit better fuel consumption. I made this decision.

I don't regret selling my Prius although I really liked it a lot...but the RX 400h offers me so much more in terms of higher quality and increased number of features. It is sooooo comfortable and such a pleasure to drive.... now, if only I could learn soon all the nuances of the complex technology of the Lexus..... I would enjoy it more.

[Lexusfreak]

I don't regret selling my Prius although I really liked it a lot...but the RX 400h offers me so much more in terms of higher quality and increased number of  features.  It is sooooo comfortable and such a pleasure to drive.... now, if only I could learn soon all the nuances of the complex technology of the Lexus..... I would enjoy it more.

←

Just read the owners manual a few times dream......you will be an expert then! B)

[OKEH1]

It appears that most RX400h owners posting information are reporting better highway MPG than city. Example, 28 hwy, 24 average.

Many owners are seemingly struggling to find the "proper" way to drive the RX400h in order to get better fuel economy....

Puzzling, VERY!

The Prius DEFINITELY has better city fuel economy.

I have NEVER heard anyone say that special driving techniques are needed for the Prius.

Yet both the Prius and the RX400h use the very same Toyota hybrid design concept.

What went wrong?

←

--------------------------

Actually, Prius Forums often report on special driving styles which raise the mpg.

Owners describe their driving technique efforts for better fuel consumption.

They are attempting to use the battery more (sometimes call "stealth mode" at certain speeds or in parked status) and the gas engine less so reports are of anticipating a stop, coasting, lower speeds, cruise control use, avoidance of "stomping on the gas", etc. etc. The same techniques should apply to the 400h although the 400h is less fuel-efficient due to size, power and design.

Yes, the Prius has better city fuel economy than the Lexus... it is a different car than the 400h. This is not puzzling.

However, it is puzzling about the few Lexus owners' reports of higher highway mpg as compared to city driving. This seems against the technological design.

←

While the mpg debate still continues on the 330/400, I have a puzzling thought that I cant seem to get out of my head.

If you were to put both the 330 and 400 in a head to head FREEWAY only test, why shouldnt the mpg be almost the same, I conclude this and may be wrong, but the 400 does not have any benefit from the electric motors on a freeway and the 400 is a fair bit heavier, I am sure there will be more frictional forces on the 400 running gear due to the motors etc than on the 330.

Maybe Lexus has improved the engine and transmission to accomodate the extra weight of batteries and motor, but again my thought would be put that same running gear in the 330 without the electrics and the car would outperform the 400 which would be embarrassing .

No big deal anyway, I am very happy with the mpg on my 330 I consistantly get 5 -10 mpg more than similar vehicles anyway so I wouldnt buy the 400 for economy reasons, I would buy a smaller more fuel efficient car, just as they do in Europe.

[SW03ES]

There is a benefit from the electric motors at highway speeds, just not as much.

[wwest]

Highway MPG, RX400h vs RX330

Assume starting out at a constant speed of 55MPH and then step on the gas to accelerate to 65MPH.

The RX330 will instantly downshift and unlock the torque converter as the engine ECU reacts to the new gas pedal position and begins to feed more fuel to the (ONLY!) engine. As you approach 65MPH and begin "dethrottling" back to cruise the transaxle will upshift and the torque converter will lock as the engine RPM declines back down for cruising.

As the RX330's engine RPMs rose the frictional and pumping losses increased and INCREASED....

The RX400h will throw in the electrics to generate the extra torque needed for acceleration allowing the engine to remain at a constant, highly optimized, RPM....

Just a guess, but.........

[skyfish400h]

If you were to put both the 330 and 400 in a head to head FREEWAY only test, why shouldnt the mpg be almost the same, I conclude this and may be wrong, but the 400 does not have any benefit from the electric motors on a freeway and the 400 is a fair bit heavier, I am sure there will be more frictional forces on the 400 running gear due to the motors etc than on the 330.

Maybe Lexus has improved the engine and transmission to accomodate the extra weight of batteries and motor, but again my thought would be put that same running gear in the 330 without the electrics and the car would outperform the 400 which would be embarrassing .

←

The drive trains are completly different. The engine is tuned and cammed differently (it doesn't even use the same thermodynamic cycle as a 330). The CVT it a HUGE difference. The drive train on the 330 would likely have HIGHER friction losses due to more moving parts and more inertia.... all of these differences would tend to make the 400 more efficient on the HWY than the 330.

You just can't compare them this way. It's like those Superman vs Spiderman aguments when you were a kid... there is no end to it.

[jj_fender]

I have noticed when cruizing on the freeway in my RX400h, the electric motors kick in at certain times, e.g., when on an easy flat or slight downgrade. This might give better overall mileage than the RX330.

I have also noticed that my average MPG goes up the more I travel on the freeway. When I travel around town my average MPG goes down. This is exactly the opposite of what I expected from the hybrid design.

[disappointed]

I have had my RX for over a week now...driven it about 350 miles.  I have found that if you drive the car no more than 65 mph on the highway (and with cruise) or on flat ground with no need to accelerate, you can get good mileage...otherwise, the car, so far, is a bust.

The reason I say this?

I have not seen any numbers above 24 mpg on my car.  No matter how gingerly or hard I drive it, I can't get the mpg up...whether I accelerate like a grandma or hit the gas 'briskly', the car's gas motor seems to suck down gas...and it seems to run virtually all the time.

Lexus stated 31/27...that's fine and dandy...but under what conditions?  I don't think drivers should have to change their driving style to get this mileage...as is the case with ANY car, if you drive it a little harder, you lose some efficiency...what's apparent with a hybrid is if you accelerate a little too much, you get lousy mileage...period!

I don't know how Lexus got away with advertising good mileage with this vehicle.  I'm seeing better performance at a tremendously greater price, and with very little efficiency gain.

If I were to receive the 31/27 with 'normal' driving conditions, I'd be very happy.  Problem is that I'm driving around at about 22-23 mpg easing the car around as carefully as I can so as to not 'over-engage' the gas motor.

I feel very misled and as of this point in time, very, very unhappy with this vehicle.  I appreciate the navi system, bluetooth, and other toys, but they pale in comparison to the importance I stressed on the improved mileage for the vehicle.

I gloated to everyone that I was getting a luxury hybrid SUV that would be getting me near 30mpg...now I'm embarassed to tell anyone I even bought the car...there is nothing special about the hybrid system other than a lot of technology...

A breakin period is, of course, in order...however, the likelihood of going from 23 mpg to near 30 is probably very slim...I guess to get there I'll always have to be driving down hill....this is pathetic.

I think Lexus has done itself a HUGE dis-service with this vehicle.  I can't imagine most people will be happy with its lower than advertised mpg...all for thousands more.  As of this date, this car is a bust...too much money for too little of what Lexus said it would do.

Once J.D. Power gets a hold of people like me, I don't see Lexus sitting number one much longer!

I am so very disappointed...I guess I should have waited a few years to see how the hybrids would turn out...had I known they'd be so disappointing, I would have put my $50,000+ somewhere else...should've waited for next MDX generation with cylinder cut-off...likely to get true 28 mpg like the Honda Odyssey...and it'll be about $10,000 less, with more room....

Lexus should be ashamed of this vehicle!

Headless

←

[disappointed]

We have driven ours for two tanks at 23 mpg.Thinking that it was an adjustment problem we took it in. We were told that we shoud not expect to get anywhere near the published 31mpg as that was only an epa estimate. We certainly weren't told this prior to spending the money. It is a very good thing that all other aspects of the car are wonderful ( ride, noise, etc.) Otherwise I would be beyond upset. I cannot help but think that since the electric only runs at 20 mph and below that some adjustment there could help. We were assured that this was not specs. The regional rep is up to 25mpg after 5000 miles so that is what we should aspire to. Welcome to the world of auto sales.

[rail88]

I've had my RX400h for about two weeks.  Got 27.9 mpg on the first tank and 28.5 mpg on the second tank.  A/C runnning the entire time, although the weather hasn't been very hot.  I estimate that I drive about 70% highway and 30% city.  Most trips are 20 minutes or longer.  For reference, I averaged 20.3 mpg in my 1999 RX300 doing the same type of driving.

So far, I'm a very happy camper.

←

Here's an update. After 2,470 miles, I'm averaging 26.6 MPG based on gas receipts. We went through our first hot spell in Maryland a few weeks ago and I noticed what appears to be a correlation between mileage and temperature. I seem to get about 1.5 MPG less in temperatures above 85 degrees. Perhaps this is because the A/C has to work harder but I'm surprised it's that significant. Anyone else noticed anything similiar?

[JasonATL]

Here's an update.  After 2,470 miles, I'm averaging 26.6 MPG based on gas receipts.  We went through our first hot spell in Maryland a few weeks ago and I noticed what appears to be a correlation between mileage and temperature.  I seem to get about 1.5 MPG less in temperatures above 85 degrees.  Perhaps this is because the A/C has to work harder but I'm surprised it's that significant.  Anyone else noticed anything similiar?

←

For me it seems clear that the A/C drains a lot. After 1,000 miles, I was in traffic on a hot day last week. I had a nearly full battery (one below the top) and it only lasted about 10 minutes (less than one mile) in crawling traffic. Without the A/C, I've made it at least 3 miles in 20 minutes or so. In fact, this was the first time I recall the ICE starting for the sole purpose of charging the battery.

When I run without the A/C, I seem to be able to go faster before the ICE kicks on. So, it appears to me that the A/C definitely burns a lot of energy (probably depending on how hard the A/C is working, too).

Having said all of that, this is no different than conventional autos. The A/C always affects MPG. I even remember turning off the A/C a few times to give me more power to get up mountains.

[patt]

Here's an update.  After 2,470 miles, I'm averaging 26.6 MPG based on gas receipts.  We went through our first hot spell in Maryland a few weeks ago and I noticed what appears to be a correlation between mileage and temperature.  I seem to get about 1.5 MPG less in temperatures above 85 degrees.  Perhaps this is because the A/C has to work harder but I'm surprised it's that significant.  Anyone else noticed anything similiar?

←

On freeway driving (65 mph) in really hot weather with the early afternoon sun shining into the car, the AC appears to cost about 1 mpg. I expect that at lower speed the mpg cost is more (less miles traveled per hour but just has much AC needed).

[thesaintjim]

Hmmm...

28MPG hwy...

24MPG....everyday use.

You do recognize that to be backward from what Lexus has promised?

←

I drive 80 miles a day, all highway for work...it can stay that way :P

[Vegas 400h]

The breakin period, I guess, will take some time...why doesn't Lexus inform us of that?  The only thing I was told was not to use cruise in the first 100 miles and to change speed a lot...

I admit I have accelerated at times quickly (like when merging onto highway)....the car does have a excellent pick-up...but the mileage cost is great!

Also, why didn't Automobile and other magazines that really praised the RX tell us exactly HOW they drove it?  Did they get new vehicles or vehicles that were already used for some time...so, past breakin period?  They got great numbers without making a big deal about how they drove the darn thing...how'd they pull that off?

Perhaps I should just take a nice 500 mile road trip...stick the thing in cruise at like 65 mpg and let the gas motor breakin nicely...will probably get over 25 mpg with this approach, eh?

Headless

←

I have gone on a 300 mile trip from sea level (LA) to 2000 feet (Vegas) and back with average of 28 mpg. That was at 800 miles on odometer, now at 4000+ with same average mpg.

[nater]

Hi to everyone, this is my first post here.

After reading through all 10 pages of this thread, I want to add some insight.

I apologize in advance if the tone of this post is condescending.

The concept of Hybrid Synergy Drive (HSD) is, pure and simple, efficiency, but not like you might think:

The idea is to deliver only as much energy as conditions require. Period.

That being said, optimum mileage will be achieved in conditions that require less energy. The car is powered entirely by gasoline. (It may be PROPELLED by electricity, but it’s still POWERED by gasoline).

The more energy demands placed on the vehicle, the more energy delivered, and consumed. The lower the energy demands placed on the vehicle, the less energy (and therefore less gasoline) consumed.

Suddenly, laws of physics and chemistry cannot be broken. You want fast acceleration uphill while towing a trailer with the A/C on high? That’s going to take some gasoline.

Most cars are so wasteful by design that optimum MPG is achieved under highway conditions. Let’s check out some rules that can’t be broken:

-The faster you go above a particular drag threshold, the more energy required. This is probably around 35 MPH for a typical car.

-Stop and Go driving is never better than continuous motion at your actual realized speed.

-The energy recovered from braking is never equal to what was required to accelerate.

-Going uphill and then down is never better than a flat surface

-changing speed consumes energy.

-Optimum gearing at all speeds is difficult to achieve without a continuously variable gear ratio.

-A/C consumes energy.

-Heating an enclosed space consumes energy

-Lights consume energy

That being said, the most efficiently a vehicle can be propelled is under optimum conditions. Those optimum conditions are on a flat surface with continuous speed of about 35 MPH with no A/C, heat or lights required. For an internal combustion powered vehicle, longer trips improve efficiency because warm up for the engine has already been achieved, so the mixture can remain lean and the cat stays hot, lubricating fluids are flowing easily, etc.

Given a particular EPA rating, why can’t you achieve it? (The issues listed here assume you don’t change the vehicle, just improving mileage in a vehicle you already own).

-A major killer of high MPG’s is aggressive driving. If you drive aggressively, you will pay in terms of gasoline, no matter what car you drive. You are making energy demands on the vehicle, and they must be met. Most aggressive drivers don’t notice any dip in MPG because they own cars that are already incredibly wasteful. In a typical V8, the energy that they are using to come up fast and ride someone’s !Removed! would otherwise be lost as heat.

-Another killer of high MPG’s is warmup/ cooldown. Warming up the engine wastes fuel, and cooling the cabin uses fuel, but hey, I’m not about to give that up. But guess what? Parking in the garage helps a lot with both (or shade in the summer).

-One more killer of high MPG’s is stop and go driving. Yes, the idling is bad, but it’s really the lost energy from accelerating and decelerating.

-Another one is overall speed. The faster you go, the more air resistance. Most cars get better mileage at highway speed, but that is simply because the transmission is so inefficient. It takes a lot to push air out of the way. The Prius is ultra-low drag, but it too suffers above a certain point.

HSD is optimized all the time. The Continuosly Variable Transmission, combined with the electric regen/ propulsion system, allows the vehicle to achieve much better mileage- if you want it to.

You want good mileage? Relax, maintain constant (slower) speed as much as possible, minimize load on the A/C and heat, and try to avoid short trips. This will help for any car, but the difference in a vehicle with a Hybrid Synergy Drive powertrain will be dramatic.

You want balls-to-the-wall power and speed all the time? You have to pay the piper. The laws of thermodynamics cannot be broken, you better be prepared to buy more fuel to make it happen. Don't believe me? Try running everywhere you would normally walk but eat the same number of calories. I guarantee you'll get skinny.

Nate

[HyBruce]

Great post, Nate!!